° = 10( √ 2)m/s 2m 4.25m 45 o A shot putter throws a 4kg shot at a 45 o angle upward with a two-dimensional velocity of 10( √ 2) m/s. The shot leaves his hand at a height of 2m and takes a projectile path off of a cliff and lands on a platform located 4.25m below ground level (Hint: Cos45 o = Sin45 o = (1/ √ 2), √ (2.25) = 1.5) Calculate the horizontal distance to the platform. (Hint: You need to calculate the time to the peak height and then the time to platform.) Draw a velocity vs. time graph with zero acceleration. Draw a velocity vs. time graph with constant-positive acceleration. Draw the distance vs. time graph, corresponding to the previous graph, and draw a line representing the average velocity. Use the velocity vs. time graph to calculate the acceleration and an equation of motion to calculate the distance.

CHAPTER 4 NEWTON ' S SE CON D LAW OF MOTION 61 Volume The quantity ofspace an object occupies. Newton's second law The acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. Newton The SI unit of force. One newton (symbol N) is the force that will give an object of mass 1 kg an acceleration of 1 m/s' . SUMMARY OF EQUATIONS Weight = mg . Fner AcceleratIon: a = --m Force = ma REV I EW QUESTIONS Force Causes Accelerati n 1. Is acceleration proportional to net force, or does accelera-tion equal net force? Friction 2. How does friction affect the net force on an object? 3. How great is the force of friction compared with your push on a crate that doesn't move on a level floor? 4. As you increase your push, will friction on the crate increase also? 5. Once the crate is sliding, how hard do you push to keep it moving at constant velocity? 6. Which is normally greater, static friction or sliding fric-tion on the same object? 7. How does the force offriction for a sliding object vary with speed? B. Slide a block on its widest surface, then tip the·block so it slides on its narrowest surface. In which case is friction greater? 9. Does fluid friction vary with speed? With area of contact? Mass and Weight 10. What relationship does mass have with inertia? 11.

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